Combustion tube



FIG. 1 is a perspective view of the combustion tube;

FIG. 2 is a front elevational view of the combustion tube, it being understood that the tube is symmetrical;

FIG. 3 is a top plan view of the combustion tube; and,

FIG. 4 is a bottom plan view o the combustion tube. 

CLAIM I claim the ornamental design for a combustion tube, as shown. 